The Dockerfile and nginx.conf are deploy infra, so nobody on the dashboard side needs to gate them. Drop the remaining owner instead of making one person the sole required approver.
The /ui/ rule sweeps in the container plumbing (Dockerfile, nginx.conf) and the checked-in tsbuildinfo, none of which are dashboard code. Exempt them so review requests land on the people who actually own that surface.
Adds ownership of litellm-proxy-extras/litellm_proxy_extras/migrations so
schema migration changes get a review request.
Also repoints the two existing entries at @yuneng-berri. GitHub's CODEOWNERS
validator was rejecting @yuneng-jiang as an unknown owner, which left the
/ui/ and _experimental/out/ rules inert.
